Baitullah Mehsud unleashed a campaign of suicide attacks and assassinations that made him the country's most-wanted man. The U.S placed a $5 million bounty on his head in March.
Pakistan's foreign minister said Friday he is "pretty certain" Mehsud was killed with his wife and guards in a missile attack two days ago.
" Various government agencies have reported so, his own followers have said so, there are people who have been to the funeral and are witness to the burial," Shah Mehmood Qureshi said Friday on BBC radio.
"With him gone, I think there is going to be an internal struggle and disarray in their ranks, I think it will set in demobilization. It is a great success for the forces that are fighting extremism and terrorism in Pakistan." Qureshi said.
An official who requested anonymity went further.
"It's 100 percent certain now," a senior member of the Pakistan government told Reuters, explaining that the intelligence services had obtained confirmation of the death from family members.
But Pakistani officials say they lack physical evidence of Mehsud's death as it was impossible to enter the Taliban controlled area in the tribal lands of South Waziristan.
An intelligence officer in South Waziristan told Reuters that Mehsud's funeral had already taken place, while Pakistani media cited their own security sources, saying he was dead.
"He was killed with his wife and he was buried in Nargosey," the officer said, referring to a tiny settlement about half a mile from the site of the attack, believed to have been carried out by a pilotless U.S. drone aircraft.
While his demise would be a major coup for Pakistani and U.S. efforts to eradicate the Taliban and al-Qaida, it won't necessarily deal a definitive blow since he has deputies who could take his place.
Taliban commanders met Friday in the lawless tribal area of South Waziristan to choose his successor, according to intelligence and militant officials who spoke with the Associated Press on condition of anonymity because of the sensitivity of the matter. It was unclear when they would reach a decision.
Mehsud had al-Qaida connections and was suspected in the assassination of former Prime Minister Benazir Bhutto.
Pakistani and U.S. intelligence officials told the AP that the CIA was behind the strike Wednesday that killed Mehsud. All spoke on condition of anonymity because of the sensitivity of the matter.
Pakistan publicly opposes the missile strikes, saying they anger local tribes and make it harder for the army to operate. Still, many analysts suspect the two countries have a secret deal allowing them.
Mehsud held a rare news conference last year in the town of Kot Kai in South Waziristan to discuss his fight against the U.S.
"It is the top desire of my life to obtain martyrdom, I have strong feelings for the martyrdom in my heart," he said, according to the AP. "To be a martyr, to be wounded or arrested we consider it as a sacrifice."
Analysts say the reason for Mehsud's rise in the militant ranks is his alliances with al-Qaida and other violent groups. U.S. intelligence has said al-Qaida has set up its operational headquarters in Mehsud's South Waziristan stronghold and neighboring North Waziristan.
A spokesman for the Afghan Taliban said their struggle would be unaffected by Mehsud's reported death.
"The Taliban's jihad against foreign forces in Afghanistan will not be affected if a Pakistani Taliban leader is killed on the other side," Afghan Taliban spokesman Zabiullah Mujahid told Reuters from an undisclosed location.
A spokesman for President Barack Obama says the White House cannot confirm the killing of Pakistan's Taliban chief but added that the people of Pakistan are now safer if reports are accurate.
White House spokesman Robert Gibbs said Friday: "We cannot confirm whether he is dead. There seems to be a growing consensus among credible observers that he is indeed dead."
Gibbs described Mehsud as a murderous thug. He said: "If he is dead, without a doubt, the people of Pakistan will be safer as a result."
---- Compiled from wire reports and other media sources